libstdc++ related bootstrap failures

[Benjamin Kosnik]

> globals.cc now contains ELF Glibc-specific asm statements such as:
> 
>   asm (".symver _ZN9__gnu_cxx8c_localeE,_ZSt8c_locale@@GLIBCPP_3.2");
> 
> which are enabled for all targets, not just GNU/Linux.  The syntax is
> of course illegal on many targets.

I've removed them for targets that don't support symbol versioning.
Update and try again, please.

-benjamin